In vitro biological activities of 6-isosteric penicillins and 7-isosteric cephalosporins.

Antibiotic and penicillinase inhibitor activities of various penicillin and cephalosporin analogs are reported. The compounds include C-6 penicillin and C-7 cephalosporin carbon, oxygen and sulfur analogs obtained by replacing the NH of the amide side chains with CH2, O and S, respectively. In almost all cases, analogs were considerably less active than the standard compounds (benzylpenicillin and cephalothin). However, some of the analogs act as penicillinase inhibitors.